Power takeoff speed control assembly

Abstract

The present invention provides a speed control system for use in maintaining the rotational speed of an output shaft of a power takeoff unit within a predetermined range. A central control unit receives signals indicative of the speed of the input gear and, in response to the received signals engages and disengages the output shaft of the power takeoff unit. The central control unit also disengages the output shaft if the system's voltage levels drop below a preset minimum.

We claim: 
     
       1. A power takeoff assembly comprising, in combination, a power takeoff unit having an input gear and an output shaft, said power takeoff unit being shiftable between an engaged position wherein said output shaft is rotationally driven by said input gear and a disengaged position wherein said output shaft does not rotate; a speed sensor means adjacent said power takeoff unit for sensing the rotational speed of said input gear;   a valve means in communication with said power takeoff unit for shifting said unit between such engaged and disengaged positions;   a control means in communication with said sensor means and said valve means, said control means including at least one electronic comparator circuit having preset operating parameters for said input gear, said circuit receiving signals from said sensor means and, directing said valve means to disengage said power takeoff unit when the operating condition of said input gear falls outside said preset operating parameters.Iadd., said operating parameters include a first speed setting and a second speed setting and said valve means operates to disengage said output shaft when the speed of said input gear exceeds such first speed setting, said valve means operates to engage said output shaft when the speed of said input gear is less than such second speed setting.Iaddend.. .[.   
     
     
       2.  The power takeoff assembly of claim 1 wherein such operating parameters include a first speed setting and a second speed setting and said valve means operates to disengage said output shaft when the speed of said input gear exceeds such first speed setting..]. .[.3. The power takeoff assembly of claim 2 wherein said valve means operates to engage said output shaft when the speed of said input gear is less than such second speed 
     
     
        setting..]. 4. The power takeoff assembly of claim .[.3.]. .Iadd.1 .Iaddend., wherein said second speed setting is lower than said first 
     
     
        speed setting. 5. The power takeoff assembly of claim 4 wherein said first and second speed settings are manually adjustable at said control means. 
     
     
           The power takeoff assembly of claim 1 wherein said power takeoff unit includes a clutch means having at least one clutch plate in communication with said output shaft or said input gear and at least one friction plate in communication with said input gear or said output shaft, said friction plate engaging said clutch plate to transfer force from said input gear to 
     
     
        said output shaft when said power takeoff unit is engaged. 7. The power takeoff assembly of claim 6 wherein said valve means operates to transfer fluid under pressure to said clutch means to actuate such engagement 
     
     
        between said clutch plate and said friction plate. 8. The power takeoff 
     
     
        assembly of claim 7 wherein said fluid is air. 9. The power takeoff 
     
     
        assembly of claim 7 wherein said fluid comprises hydraulic fluid. 10. The power takeoff assembly of claim 4 wherein said control means includes a time delay means, said time delay means operating during initial start-up of said power takeoff unit to disengage said output shaft for a 
     
     
        predetermined period of time. 11. The power takeoff assembly of claim 10 wherein said time delay means includes an overspeed check circuit, said overspeed check circuit disengaging said output shaft during initial start-up until said speed sensor signals that the speed of said input gear 
     
     
        is not in excess of such first speed setting. 12. The power takeoff assembly of claim 10 wherein said time delay means includes a low voltage shut-down circuit, disengaging said output shaft during initial start-up if the voltage level received by said control means is less than a 
     
     
        predetermined minimum. 13. The power takeoff assembly of claim 4 wherein said control means includes a second low voltage shut-down circuit, said second low voltage shut-down circuit disengaging said output shaft anytime during operation of said power takeoff unit if the voltage level received 
     
     
        by said control means is less than a predetermined minimum. 14. The power takeoff assembly of claim 4 further including switch means adjacent said power takeoff unit for determining whether said output shaft is engaged. 
     
     
          . The power takeoff assembly of claim 14, wherein said control means includes an indicator light means in communication with said switch means, said indicator light means being lighted when said output shaft is 
     
     
        engaged. 16. The power takeoff assembly of claim 4 further including a second indicator light located on said control means for indicating an 
     
     
        overspeed condition of said input gear. 17. The power takeoff assembly of claim 4 wherein said control means further includes a central control unit positioned proximate the location the operator of said power takeoff unit is positioned during operation of said power takeoff unit, said central 
     
     
        control unit containing said electronic comparator circuits. 18. The power takeoff assembly of claim 17 wherein said central control unit includes a switch means for determining whether said output shaft is engaged, a first indicator light engaged with said switch means for indicating the engagement of said output shaft, and a second indicator light for indicating an overspeed condition of said input gear.